The present invention relates to testing systems and methods for verifying the operation of an external programming device used to monitor and control an implantable device, such as an implantable pacemaker. More particularly, the present invention relates to a self contained testing system and method that verifies the operation of the communication circuits within the external programming device that are used to establish a telemetry link with the implantable device.
Implantable devices are implanted in a human or animal for the purpose of performing a desired function. This function may be purely observational or experimental in nature, such as monitoring certain body functions; or it may be therapeutic or regulatory in nature, such as providing critical electrical stimulation pulses to certain body tissue, nerves or organs for the purpose of evoking a desired response. The modern implantable demand pacemaker is an example of an implantable device that performs both observational and regulatory functions, i.e., it monitors the heart to make sure it beats at an appropriate rate; and if not, it causes an electrical stimulation pulse to be delivered to the heart in an attempt to force the heart to beat at an appropriate rate.
In order for an implantable device to perform its functions at minimum inconvenience and risk to the person or animal within whom it is used, some sort of non-invasive telemetry means must be used to allow data and commands to be easily passed between the implantable device and an external device. Such external device, known by a variety of names, such as a controller, programmer, or monitor, will generally be referred to herein as an "external programming device", where "external" connotes non-implanted. The external programming device provides a convenient mechanism through which the operation of the implantable device can be controlled and monitored, and through which data sensed or detected by the implantable device can be transferred to the external programming device where it can be read, interpreted, or otherwise used in a constructive manner.
A commonly known implantable device is the implantable pacemaker. All known implantable pacemakers utilize a corresponding external programming device to control (program) and monitor their operation. While the present invention is not limited to the external programming devices used with implantable pacemakers, such external devices comprise the best presently known application for the present invention. The present invention can thus be better understood and appreciated if a basic understanding of such devices, i.e., implantable pacemakers and their corresponding external programmers, is also known. A description of a pacemaker, for example, including a description of some of the special features that may be included in a pacemaker, may be found, e.g., in U.S. Pat. Nos. 4,686,988, 4,712,555 and 4,788,980. Similarly, a description of a modern external programming device may be found in U.S. Pat. No. 4,809,697. A description of some of the different types of telemetry systems that may be used to establish a communication link between an implantable pacemaker and an external programming device may be found, e.g., in U.S. Pat. No. 4,681,111 and in applicant's copending patent application, "High Speed Digital Telemetry System For Implantable Device," Ser. No. 07/391,080, filed herewith. These patents and application are all assigned to the same assignee (or a related assignee) as is the present application, and are all incorporated herein by reference.
One of the difficulties associated with using an external programming device to monitor and control an implanted device is being able to quickly determine the source of a potential malfunction when such potential malfunction is detected. For example, if status data received from the implantable device indicates some circuit of the implantable device is not functioning properly, it must quickly be determined whether the circuit in the implantable device is, in fact, malfunctioning; or whether the telemetry circuits and data processing circuits within the external programming device have failed to present the data properly. Similarly, if a programming command is sent to the implantable device from the external programming device, but the programming device fails to respond to the command properly, a determination must be quickly made as to whether the correct command was in fact sent to the implantable device by the external programmer or whether something is in fact wrong with the implantable device.
Heretofore, determinations such as are described in the previous paragraph have required that special diagnostic tests be performed in an attempt to isolate the source of the problem. Besides taking a significant amount of time to perform, it is not uncommon for such diagnostic tests to require a thorough knowledge of how the pacemaker and external programmer operate, as well as the use of additional test equipment, such as multimeters, signal generators, oscilloscopes, and the like. Further, personnel trained in the use of such test equipment are also needed. Unfortunately, such additional test equipment and/or skilled personnel is not always readily available at the time a determination as to the source of a problem must be made. Moreover, even when a particular diagnostic test is performed, and the source of a potential problem is identified, the results of the test may not present sufficient data to allow the appropriate corrective action to be taken. Before such corrective action can be taken, it is not uncommon for very extensive and comprehensive tests to be made, requiring still more time, more test equipment, and technically skilled personnel to perform the tests. Hence, it is evident that what is needed is a comprehensive test that can be performed easily and rapidly to accurately determine the source of a potential malfunction, as well as appropriate corrective action, without requiring either special test equipment or technically skilled personnel. Such comprehensive tests could not only greatly facilitate diagnostic evaluation of implantable devices in actual use, i.e., devices implanted in patients, but could also be very useful during the manufacture and initial test of such devices at the manufacturing facility.
In the absence of technically trained personnel, there is also a problem when using implantable devices of knowing when a particular test should be performed. For example, in the case of implantable medical devices, where the proper operation of the implantable device, and its corresponding external programming device, may present a life-threatening situation, it may be preferable to check the performance of the external programming device on a periodic basis. A medical doctor or medical technician (who is highly trained medically, and is trained relative to how to use an external programming device, but may nonetheless lack the technical skills required to thoroughly understand the external programming device), may not know or appreciate when such periodic tests should be performed. Further, a medical doctor or medical technician, preoccupied with other more pressing concerns, may simply forget to perform periodic tests. What is needed, therefore, is a self-test that is built-in to the external programming device and that conducts certain key tests automatically at prescribed times during the operation of the device.
Another problem commonly encountered in the use of implantable devices is compatibility with the external programming device. It is not uncommon, for example, in the medical implantable device field (e.g., pacemakers) for a particular pacemaker manufacturer to have several models of pacemakers implanted in patients. Each pacemaker model may include a different type of telemetry system, requiring a different type of external programming device for use therewith. Hence, a doctor (or other medical personnel) may need several different models of external programming devices in order to properly monitor all of his or her patients, each of whom may have a different model pacemaker implanted in his or her body. Keeping track of which external programming device is to be used with which patient, as well as which tests should be performed on all the different models of external programming devices, may become quite burdensome. Hence, what is needed is a universal external programming device that can be used with all models of a particular manufacturer's implantable devices, and that includes self-test features built therein that automatically or selectively perform the appropriate tests at the appropriate times.
The present invention advantageously addresses the above and other needs.